[Terrain] Add move/scale wizard

[PolEpie]

Pull Request

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Summary

Just a little panel to let you scale / move terrain easily with bound visualisation

Motivation & Context

The terrain tool is really good but once you started doing your terrain and then realize fuck i wanted it a bit bigger / higher, you're fucked, even like if you wanted to dig deeper, you can't.

So i made something that let us scale (as before with uniform scaling) but also scale while keep actual geometry size (so you basically keep what you had and then earn more space)

And a tool to translate the height data (like moving up / down / left / right)

Implementation Details

Ngl jean claude helped me a lot but i was like that might be helping you as a good base

• So first i added a TerrainBoundPreview that let us visualize what's ur terrain limit, and that's useful for after you'll see
• Then i remove the input to change terrain height / wide to a non editable input with 2 button
• And so into TerrainImportHelper there is now ShiftContent that will manage the x and y translation
• I also added OffsetHeights that will manage the z translation so height clamped to to prevent to high values / negative ones
• And lastly the CanvasResize that doesnt mutate the input but return a modified array so we can support undo
• And i also added a green / red zone indicator when i translate a zone that will lose detail / have some part "interpolated"

Screenshots / Videos (if applicable)

2026-08-10.02-00-20.mp4

Checklist

• Code follows existing style and conventions
• No unnecessary formatting or unrelated changes
• Public APIs are documented (if applicable)
• Unit tests added where applicable and all passing
• I’m okay with this PR being rejected or requested to change 🙂